JP4779852B2 - Portable navigation device and navigation program - Google Patents

Description

  The present invention relates to a portable navigation device and a navigation program for acquiring current position information and traveling direction information and performing navigation.

  In a conventionally known navigation device installed in an automobile, navigation is performed by detecting the position of the vehicle using information such as a GPS (Global Positioning System) signal, a gyro sensor, and a speedometer. In recent years, portable navigation devices that perform navigation by mounting a GPS chip on a portable PDA (Personal Digital Assistants) device have also been developed.

  FIG. 4 is a diagram schematically showing the processing in the conventional portable navigation device. The GPS chip 41 conforms to the NMEA (National Marine Electronics Association) standard via the UART (Universal Asynchronous Receiver Transmitter) communication unit 42. Based on the message format data (hereinafter referred to as NMEA message) is output.

  This NMEA message is taken in from the COM port of the CPU by the virtual COM driver 43, and is output to the map navigation application 44 that is the higher-level application. The map navigation application 44 performs navigation by referring to the current position information and direction information from the NMEA message.

Patent Document 1 discloses a portable navigation device that is connected to a vehicle and receives a gyro sensor and a vehicle speed pulse signal from the vehicle.
JP 2005-195387 A

  However, in the conventional portable navigation device, when the device is turned on or during low speed movement, GPS signals cannot be received normally in tunnels, high-rise buildings, underground, etc. In some cases, the direction could not be determined.

Further, in the portable navigation device described in Patent Document 1, it is possible to determine the traveling direction of the vehicle from the signal of the gyro sensor or the like. For this purpose, it is necessary to connect to the vehicle while being portable.
The present invention has been made in view of the above circumstances, and its purpose is to carry a mobile phone capable of automatically acquiring highly accurate azimuth information and performing navigation even when azimuth information cannot be correctly received from a GPS signal. It is to provide a type navigation device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. The invention according to claim 1 receives a GPS signal, and receives first GPS information indicating the current position and traveling direction, and the moving speed of the apparatus. A position detecting means for outputting velocity information indicating a position, a geomagnetic sensor for detecting geomagnetism and outputting second azimuth information, and a determination for determining the accuracy of the first azimuth information based on a predetermined criterion A first azimuth information when it is determined to be accurate by the determination means, and a selection means for selecting the second azimuth information when it is determined not accurate, and the position detection means ; and a navigation means for navigating the azimuth information selected by the selecting means and the detected position information, said determination means normally be able to receive GPS signals at said position detecting means and the moving speed of the apparatus Tokoro When the value is equal to or greater than the value, it is determined that the first azimuth information is accurate, and the position detection unit cannot correctly receive the GPS signal or the moving speed of the device is less than a predetermined value. It is a portable navigation device characterized in that it is determined that the first orientation information is not accurate .

According to a second aspect of the present invention, in the first aspect of the present invention, the position of the device after a predetermined time is predicted, and it is determined whether or not the first azimuth information can be obtained at the position. The information processing apparatus further includes one prediction unit, and the selection unit selects the second direction information when the first prediction unit determines that the first direction information cannot be obtained .

According to a third aspect of the present invention, there is provided the second aspect of the present invention , wherein the position of the device after a predetermined time is predicted and whether or not there is an influence on the detection of geomagnetism at the position. The information processing apparatus further includes a prediction unit, and the selection unit selects the first azimuth information when it is determined that the second prediction unit has an influence on detection of geomagnetism .

According to a fourth aspect of the present invention, a position detection procedure for receiving a GPS signal and inputting position information of a current location, first direction information indicating a traveling direction, and speed information indicating a moving speed to a computer , A procedure for inputting the second azimuth information obtained based on geomagnetism, a determination procedure for determining the accuracy of the first azimuth information based on a predetermined determination criterion, and a determination procedure that is accurate. If it is determined that the first direction information is selected, if it is determined that the second direction information is not accurate, a selection procedure for selecting the second direction information, and navigation that performs navigation based on the position information and the direction information selected in the selection procedure. When the GPS signal can be normally received in the position detection procedure and the moving speed is equal to or higher than a predetermined value, the first direction information is accurate in the determination procedure. In order to determine that the first azimuth information is not accurate in the determination procedure when the GPS signal is not normally received in the position detection procedure or the moving speed is less than a predetermined value. It is a navigation program.

  According to the present invention, when the first azimuth information based on the GPS signal is not accurate, the second azimuth information obtained by the geomagnetic sensor is selected by the selection means and used for navigation. Even in an environment where reception is not possible normally or when the device is moving at a low speed, the navigation means can perform navigation using highly accurate azimuth information.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram showing a configuration of a portable navigation device according to an embodiment of the present invention. In FIG. 1, an antenna 11 of the portable navigation device 1 is an antenna for receiving a radio wave signal from a GPS satellite (not shown).

  The GPS receiving unit 12 (position detecting means) includes a GPS chip that demodulates a radio signal received from a GPS satellite and generates an NMEA message, and a UART communication unit that communicates with the CPU 13 by UART. The NMEA message includes speed information and the like in addition to the current position information and azimuth information represented by the latitude / longitude of the portable navigation device 1 (or altitude in the case of the three-dimensional mode).

  The CPU 13 is a CPU (Central Processing Unit) that controls each unit in the portable navigation device 1. The geomagnetic sensor unit 14 includes a geomagnetic sensor that calculates and outputs a direction from the detected geomagnetism, and an I2C communication unit that communicates with the CPU 13 through I2C. The geomagnetic sensor unit 14 may detect biaxial geomagnetism or may detect triaxial geomagnetism.

  The RAM 15 is a RAM (Random Access Memory) that provides a work area or the like for use in data storage or the like while the CPU 13 is operating. The ROM 16 is a ROM (Read Only Memory) that stores programs to be executed by the CPU 13 and various data.

  The display unit 17 is a display that displays images, characters, and the like based on display signals input from the CPU 13. The operation unit 18 inputs a user operation and outputs the input content to the CPU 13. The bus line 19 connects each part in the portable navigation apparatus 1 to each other.

Next, the operation of the above-described embodiment will be described with reference to FIGS.
FIG. 2 is a diagram showing processing in the portable navigation device 1 of FIG. In FIG. 2, reference numerals 21 and 22 indicate the configuration of the GPS receiving unit 12, and reference numerals 23 and 24 indicate the configuration of the geomagnetic sensor unit 14. Reference numerals 25 to 28 denote software that operates on the CPU 13.

  The NMEA message output from the GPS chip 21 is output to the COM port of the CPU 13 via the UART communication unit 22. The virtual COM driver 25 takes in the NMEA message input to the COM port and outputs it to the virtual COM software 27.

  On the other hand, the azimuth information output from the geomagnetic sensor 23 is output to the I2C port of the CPU 13 via the I2C communication unit 24. The I2C driver 26 takes in the azimuth information input to the I2C port and outputs it to the virtual COM software 27.

  The virtual COM software 27 once reads and analyzes the NMEA message from the GPS chip 21, and determines whether or not the direction information (first direction information) in the NMEA message is reliable (determination means). If it is determined that the communication is reliable, the virtual COM software 27 outputs the NMEA message to the map navigation application 28 as it is.

  On the other hand, if it is determined that the information is not reliable, the virtual COM software 27 replaces the azimuth information in the NMEA message with the azimuth information (second azimuth information) from the geomagnetic sensor 23, and converts the replaced NMEA message to the map navigation application. To 28.

  The map navigation application 28 performs navigation processing based on information in the NMEA message input from the virtual COM software 27. Therefore, the map navigation application 28 can always use highly accurate direction information regardless of whether the direction information in the NMEA message is from the GPS chip 21 or the geomagnetic sensor 23.

  Next, details of processing in the virtual COM software 27 will be described with reference to FIG. FIG. 3 is a flowchart showing a flow of processing performed by the virtual COM software 27.

  In FIG. 3, when the CPU 13 inputs an NMEA message from the GPS chip 21 and the NMEA message is acquired by the virtual COM software 27 via the virtual COM driver 25 (step S301), the virtual COM software 27 receives the NMEA message. Is analyzed (step S302).

  In the analysis of the NMEA message, it is first determined whether or not the signal from the GPS satellite has been correctly received (Valid) (step S303). If it is determined that it has not been correctly received (step S303: No), the process proceeds to step S308, and if it is determined that it has been correctly received (step S303: Yes), the process proceeds to step S304.

  In step S304, the virtual COM software 27 determines whether or not it is moving from the speed information included in the NMEA message. When it is determined that it is not moving (step S304: No), the process proceeds to step S308, and when it is determined that it is moving (step S304: Yes), the process proceeds to step S305.

  In step S305, the virtual COM software 27 determines from the speed information included in the NMEA message whether the moving speed is not less than a predetermined speed (during low-speed movement). If it is determined that the vehicle is moving at low speed (step S305: No), the process proceeds to step S308. If it is determined that the vehicle is not moving at low speed (step S305: Yes), the process proceeds to step S306.

  In step S306, the virtual COM software 27 determines whether or not the accuracy of the GPS signal is sufficient from the accuracy information included in the NMEA message. When it is determined that the accuracy of the GPS signal is not sufficient (step S306: No), the process proceeds to step S308, and when it is determined that the accuracy of the GPS signal is sufficient (step S306: Yes), the process proceeds to step S307.

  When it is determined Yes in all of Steps S303 to S306, the virtual COM software 27 determines that the azimuth information of the NMEA message input from the GPS chip 21 is accurate and uses it as it is (Step S307).

  On the other hand, if it is determined No in any of Steps S303 to S306, the virtual COM software 27 determines that the direction information of the NMEA message input from the GPS chip 21 is not accurate, and the direction input from the geomagnetic sensor 23. Replace with information (step S308).

  After the process of step S307 or step S308 is completed, the virtual COM software 27 outputs an NMEA message to the map navigation application 28 (higher level application).

  As described above, in this embodiment, the NMEA message from the GPS chip 21 is once read and analyzed by the virtual COM software 27, and when it is determined that the azimuth information in the NMEA message is correct, it is used as it is, and the azimuth information is incorrect. In the situation assumed, the azimuth information in the NMEA message is rewritten with the azimuth information detected by the geomagnetic sensor 23.

  Therefore, the virtual COM software 27 can always provide accurate direction information to the map navigation application 28. For this reason, the map navigation application 28 can always display the map on the display unit 17 by rotating the map so that the traveling direction is always upward, for example, according to the traveling direction of the user. Become.

  In this embodiment, the virtual COM software 27 analyzes the NMEA message to determine the accuracy of the azimuth information of the GPS chip 21, but the map navigation application 28 uses the azimuth information by the GPS chip and the azimuth information by the geomagnetic sensor. Which direction should be selected may be determined from the current position and the traveling direction, and the azimuth information selected by the virtual COM software 27 may be switched.

  Specifically, when the GPS navigation application 28 is expected to go to a place where the GPS signal is difficult to enter, the map navigation application 28 instructs the virtual COM software 27 to select the direction information of the geomagnetic sensor, and a place with a strong magnetic field (such as an iron bridge) ( For example, the map navigation application 28 may instruct the virtual COM software 27 to select azimuth information by the GPS chip if it is expected to go to a place that affects geomagnetic detection.

  In the configuration in which the azimuth information is acquired using only the GPS signal, the azimuth information cannot be obtained accurately in a situation where the GPS signal cannot be normally received, and the azimuth information is acquired using only the geomagnetic sensor. Then, in the strong magnetic field, since the geomagnetism cannot be accurately detected, the azimuth information is also inaccurate, but it is configured to acquire both the azimuth information based on the GPS signal and the azimuth information based on the geomagnetic sensor. It is possible to always obtain appropriate azimuth information by selecting the higher accuracy from the azimuth information flexibly.

  As mentioned above, although embodiment of this invention was explained in full detail, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

  INDUSTRIAL APPLICABILITY The present invention is suitable for use in a portable navigation device that acquires current position information and travel direction information and performs navigation.

It is a block diagram which shows the structure of the portable navigation apparatus which concerns on one Embodiment of this invention. It is a figure which shows the process in the portable navigation apparatus 1 of FIG. It is a flowchart which shows the flow of the process performed with the virtual COM software 27 of FIG. It is the figure which showed typically the process in the conventional portable navigation apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Portable navigation apparatus, 11 ... Antenna, 12 ... GPS receiving part, 13 ... CPU, 14 ... Geomagnetic sensor part, 15 ... RAM, 16 ... ROM, 17 ... Display part, 18 ... Operation part, 19 ... Bus line, DESCRIPTION OF SYMBOLS 21 ... GPS chip, 22 ... UART communication part, 23 ... Geomagnetic sensor, 24 ... I2C communication part, 25 ... Virtual COM driver, 26 ... I2C driver, 27 ... Virtual COM software, 28 ... Map navigation application.

Claims (4)

Position detecting means for receiving a GPS signal and outputting position information of the current position, first direction information indicating a traveling direction, and speed information indicating a moving speed of the device ;
A geomagnetic sensor that detects geomagnetism and outputs second orientation information;
Determination means for determining the accuracy of the first orientation information based on a predetermined determination criterion;
When it is determined that the determination unit is accurate, the first direction information is selected, and when it is determined that the determination unit is not accurate, the selection unit selects the second direction information;
Navigation means for performing navigation based on the position information detected by the position detection means and the orientation information selected by the selection means ,
The determination means determines that the first azimuth information is accurate when the position detection means can normally receive a GPS signal and the moving speed of the device is a predetermined value or more, and the position detection means The portable navigation device is characterized in that the first azimuth information is determined to be inaccurate when the GPS signal cannot be normally received or when the moving speed of the device is less than a predetermined value . A first prediction means for predicting the position of the device after a predetermined time and determining whether or not the first orientation information can be obtained at the position;
  When the first prediction means determines that the first azimuth information cannot be obtained, the selection means selects the second azimuth information.
  The portable navigation device according to claim 1. A second prediction means for predicting the position of the device after a predetermined time and determining whether or not geomagnetic detection is affected at the position;
  The selection means selects the first azimuth information when the second prediction means determines that the detection of geomagnetism is affected.
  The portable navigation device according to claim 1. On the computer,
A position detection procedure for receiving a GPS signal and inputting position information of the current position, first direction information indicating a traveling direction, and speed information indicating a moving speed ;
A procedure for inputting second orientation information obtained based on geomagnetism,
A determination procedure for determining the accuracy of the first orientation information based on a predetermined determination criterion;
When it is determined that the determination procedure is accurate, the first azimuth information is selected, and when it is determined that the determination procedure is not accurate, the second azimuth information is selected.
A navigation procedure for performing navigation based on the position information and the orientation information selected in the selection procedure,
When the GPS signal can be normally received in the position detection procedure and the moving speed is equal to or greater than a predetermined value, the first direction information is determined to be accurate in the determination procedure, and the GPS is detected in the position detection procedure. A navigation program for causing the determination procedure to determine that the first azimuth information is not accurate when a signal cannot be normally received or when the moving speed is less than a predetermined value .

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